Leave it to Beavers

How researchers from the Pacific Northwest and Great Basin are working with the toothy, hardworking beaver to restore river watersheds under threat from climate change

Meghan Kearney, Nicole DeCrappeo, and Lisa Hayward Watts

The North American Beaver (Photo courtesy of hehaden, Flickr Creative Commons.)

Our changing climate is altering Northwest watersheds at an increasing rate. Many watersheds are suffering from drying streams, changes in vegetation, and loss of habitat connectivity for fish, wildlife, and plants. These changes threaten our natural and cultural resources, inspiring researchers from the Rocky Mountains to the Pacific coast to better understand, conserve, and restore natural systems using science, traditional knowledge, and good old trial-and-error. Now they’re turning to an unexpected and hardworking ally—the North American beaver, a remarkable water engineer.

Climate in the Northwest is changing, as it is elsewhere in the world. Much of the Northwest has long been characterized by wet winters and dry summers, but a changing climate is expected to increase temperatures and exaggerate seasonal patterns of precipitation so that winters get wetter and summers drier. At the same time, reduced snowpacks and increased evapotranspiration will limit surface and ground water even further. The Southwest is facing similar, more progressed challenges, where long-term drought is already changing stream flow regimes.

Given these projected changes, residents, resource managers, and scientists in these two regions face critical questions like: How will streams and ecosystems, already altered by human activities, respond to a warming future? Are there actions we can take now to increase the capacity of the land to keep providing key resources, livelihoods, and ecosystem services in the future? What strategies for restoring and improving watersheds are most effective, given future climate change? Can we simultaneously maintain human resource use while retaining critical ecosystem functions?

Drawing on research from around the nation the Guidebook explains the benefits of beaver reintroduction to areas where streams are changing. There was a time in the not-too-distant past when beavers swam the rivers, lakes, and streams of the Northwest by the millions. During the early 19th century, Hudson Bay trappers caught over 200,000 beavers in Oregon’s Silvies River basin alone. Evidence of former beaver populations still exists in the form of remnant meadows, abandoned and decomposed beaver dams, and geologic rock layer evidence of former beaver lakes now filled with sediment. Loss of beaver populations combined with widespread grazing has contributed to the deepening of stream channels and lowering of floodplains, the loss of wet meadows and riparian habitats, and the invasion of valley bottoms by upland tree species in some parts of the Northwest.

As pilot projects have demonstrated, much of what was lost by removing beaver can potentially be restored by reintroducing them. Beavers initiate ecological changes that can recreate wet meadows and riparian woodlands in valley bottoms. Beaver reintroduction is a restoration strategy that has many benefits for fish, animals, plants, and people—such as allowing ranchers to grow grass in previously inhospitable, dry valley bottoms and allowing for livestock grazing or the harvest of hay to improve ranch economics. Reestablishing wet meadows also introduces natural fire breaks on the landscape that stop or slow down wildfires.

While the “whys” of beaver reintroduction may be clear, the “hows” are often not. The Guidebook was developed in response to numerous requests from resource managers on where, when, and how to use beaver reintroduction for restoration. It has been called the most comprehensive effort to date explaining how best to undertake beaver reintroductions.

The Guidebook is the result of exhaustive literature review augmented by multiple workshops and a year’s worth of input from experts from across the Pacific Northwest. Now in the hands of natural resource managers, best practices from the Guidebook are being implemented in restoration projects around the globe.

Beaver in Colorado Restoration

The Guidebook is being used by practitioners across North America. One user is Mark Beardsley of EcoMetrics, a Colorado-based ecological consulting company specializing in the scientific assessment and monitoring of stream, riparian, and wetland systems. Beardsley and his team work closely with conservation practitioners from federal, state, and local governments. He says beavers are a perfect fit for the type of restoration work he does, and he’s on a mission to get people to recognize beaver-mediated systems.

“These beaver-mediated systems seemed to exhibit so many of the things everyone says they like in a good functioning stream: diverse and plentiful terrestrial and aquatic habitats, wetland support, floodplain connectivity, water storage, flood reduction, base flow maintenance. I could go on,” says Beardsley.

Beardsley was first introduced to the Guidebook by Kent Woodruff, a biologist with the USDA Forest Service and a member of the core Beaver Workgroup that pioneered the document. Beardsley says the Guidebook has been extremely helpful in his work, adding that one of the biggest benefits of the book is how it has made him aware of the different techniques and approaches others are using around beavers.

“I refer to [the Guidebook] for treatment designs and as a reference for my clients and other audiences who want to learn more about the role of beaver and their potential use in restoration,” he says. Beardsley says using beavers in restoration has the dual benefit of reintroducing the animals to their previous habitat and restoring that habitat in the process.

Beavers in Idaho

A few states northwest of Beardsley sits Susan Frior, a partner in the environmental engineering firm TerraGraphics. The firm, based out of Moscow, Idaho, provides river restoration services, from engineering to water resource services, for clients around Idaho, Montana, and Washington. Frior says her firm is no stranger to dealing with beaver.

“The most common conservation goals that we address are rehydrating meadow ecosystems and restoring habitat for Endangered Species Act-listed fish, especially steelhead, coho and Chinook salmon, and bull trout,” explains Frior.

Frior says dams built by beavers are excellent for rehydrating ecosystems. Beaver dams create surface pools and ponds that help expand riparian and wetland habitats. Frior says she has seen this in practice and is now a firm believer that beavers should be a strong ally in restoration efforts.

Nowhere is this more evident, says Frior, than in her firm’s efforts to restore sections of watershed along the Potlatch River in northern Idaho. To restore the flow and bring rivers back to their historic channels, her firm constructed Beaver Dam Analogs, man-made structures that mimic beaver dams. She says she got the idea for the analog dams and instructions on how to build them from the Guidebook.

“The Guidebook contains the best literature review on beavers that I know of, and I refer to it often when specific questions arise,” says Frior.

Frior also attributes to the Guidebook an even larger benefit: creating partnerships that have helped her connect with a new community.

“The Guidebook has added to the body of knowledge that we rely upon, but it’s the community and learning how to do this work together that is of the greatest value to me,” says Frior.

With interest in implementing techniques outlined in the Guidebook continuing to grow, the guide has established itself as a quintessential tool for beaver restoration. Meant to be a fluid document, the Guidebook is also being continually improved as practitioners like Frior and Beardsley utilize it in individual efforts and have additional info to offer the topic.

In addition to informing on-the-ground efforts, the Guidebook is a coffee-table conversation starter that has brought together an entire community of restoration groups and entities that work with beaver. It has led to further efficiency, cost leveraging, and has facilitated one of the most important benefits in conservation: collaboration.

What Do You Do When You Can’t Reintroduce Beaver?

As beneficial as they are when they work, beaver reintroductions still face many challenges. Often, beavers’ required foods—mostly aspen, cottonwood, and willow—may be unavailable or in short supply in certain areas because of changes in water ways and ecology, further effects of beaver removal. To reintroduce and retain beaver, there must first exist beaver habitat. This requires raising water tables, an effort now being conducted by researchers using artificial beaver dams (ABDs). ABDs are engineered structures of rock, wood, or other materials that partially dam channels, creating many of the same ecological effects as beaver reintroductions.

Beaver reintroduction, facilitation of beaver dam construction, and construction of structures that mimic beaver dams are techniques that are being explored in the Great Basin for restoring incised streams, recreating wet meadows, and building resilience against future droughts. Implementation of these options depends on perceived costs and benefits, which differ among land managers.

The Northwest Climate Science Center (NW CSC), U.S. Department of Agriculture NW Regional Climate Hub, and Great Basin LCC have jointly funded a multidisciplinary project focused on how these low-rise ABDs can help reconnect incised streams to their floodplains and increase wet meadow habitat in rangelands. The project team includes hydrologists, ecologists, GIS specialists, social scientists and, importantly, private land owners and ranchers. Together, they’re working to better understand the multiple dimensions associated with restoring beaver or mimicking their transformative influence as ways to modify landscape features to provide climate resilience. Notably, the project also examines ranchers’ attitudes toward both artificial dams and beaver reintroductions as well as the economic costs and benefits of these restoration strategies.

Scott Campbell, president and owner of Silvies Valley Ranch in eastern Oregon, is a project collaborator and rancher whose family has pioneer roots in the area. Starting in the late 1950s, Silvies Valley Ranch passed through the hands of various owners who harvested the land’s timber, crops, livestock, and wildlife but did little to build or maintain a working cattle ranch with valuable natural environmental assets. When the Campbell family acquired Silvies in 2007, they set out to create a new model for ranches throughout the United States—one that valued and prioritized natural ecosystem processes, hydrologic connectivity, and fish and wildlife habitat as highly as livestock grazing and hay cultivation. They installed ABDs on a few of the ranch’s creeks in the mid-2000s and saw astonishing results. As Campbell puts it, “These structures started the process for restoring our sensitive watersheds by conserving our most important natural resource: water. We have seen the ABDs bring back wet meadows and riparian areas within one year; dry area plants like pine and sagebrush drown and retreat to their natural areas, making a long green riparian area that stops wildfires naturally; a multitude of long-lost species from insects to birds re-inhabit the new habitat; and new late-season water (from water slowed behind ABDs) appear in the lower part of the watershed, which helps fish and other species thrive. After 10 years, we’re still seeing ever-improving habitat and increased forage production and land values—all without infringing on water rights.”

The project team also works with ranchers who are not necessarily friendly to beaver reintroduction, but may be interested in low-rise rock dams to help increase water availability during summer months and “green” their rangelands. The team has been conducting interviews with ranchers in eastern Oregon and northern Nevada, where beaver-oriented restoration is currently underway on private land and public grazing areas. The team is particularly interested in ranchers whose operations have been affected by the presence of beavers, along with a variety of federal and state land managers, wildlife biologists and watershed council members.

The project team has already contacted over 100 land managers from government and private organizations to determine their current and past use of beaver and ABDs in restoration of rangeland streams across the Great Basin and the degree of success land managers have had using these techniques.

There has been a sharp increase in the number of projects using beaver and ABDs since 2000. Most projects involve moving nuisance beaver out of urban areas or areas where they would otherwise be killed and re-locating them to streams in need of restoration. Successful projects report increased wildlife and plant diversity and higher water storage at streams where beaver were introduced. However, many projects were not monitored after their completion, leaving much for the researchers to learn about the biological, hydrological, and social responses to beaver reintroduction and ABDs.

This summer, the team will sample streams with and without beaver or ABDs to assess how biological diversity responds to these management techniques. The researchers will do this by collecting “environmental DNA” from streams—put simply, they’ll be able to detect the presence of various stream organisms by filtering water samples and then analyzing the samples for the species’ DNA. The team may also be able to detect terrestrial animals like bats, birds, and mammals living near streams in riparian areas or visiting streams as water sources. The researchers expect to find higher levels of biodiversity in streams with beavers or ABDs, as the wet meadows and riparian habitat that result can harbor a greater number of unique plants and animals.

Done right, beaver reintroduction and the use of ABDs may help address some of the impacts brought about by our changing climate. Healthy watersheds produce and sustain healthy cultural and natural resources. Through collaborative projects like those discussed above, practitioners are learning to better use beaver introduction and ABDs to restore and protect watersheds for generations to come.